Information processing apparatus and information generation method

ABSTRACT

An information processing apparatus includes: a reception unit configured to receive a packet string in which packet groups including data on a plurality of video frames and having an identifier indicating a beginning of the video frame assigned to respective packets including each initial part of the plurality of video frames are arranged in a video reproduction order; a counting unit configured to count a number of received packets corresponding to each of the plurality of video frames based on respective initial packets in the packet string; and a generation unit configured to generate video quality estimation information for each of the plurality of video frames to estimate a quality of the video in which the plurality of video frames are decoded on a reception terminal based on the number of received packets corresponding to each of the plurality of video frames.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2009-267220, filed on Nov. 25,2009, the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to an informationprocessing apparatus for generating information used for estimating aquality of a video distributed on a network.

BACKGROUND

A service for distributing a high image quality video or a high soundquality audio via the internet includes, for example, IPTV (InternetProtocol TeleVision) and other services. According to the IPTV, adegradation in quality of the video or audio at a reception terminal isexpected because of a loss of transferred packets or the like. A videoquality estimation apparatus is proposed for estimating the quality ofthe video to be distributed in a case where the degradation in qualityof the reception video and the reception audio at the reception terminalis expected.

A video quality estimation apparatus receives and decodes a video signalwhich is converted and sent into a packet string, decides apredetermined parameter as an intermediate parameter at least on thebasis of packet loss information before the decoding of the videosignal, analyzes the decoded video signal to determine a degradationtype of the video signal, and estimates a video quality of the videosignal after the decoding on the basis of the intermediate parameter andthe degradation type. For example, Japanese Laid-open Patent PublicationNo. 2007-19802 discloses an estimation of a subjective quality of avideo signal by extracting a media characteristic amount of a decodedvideo signal. Also, Japanese Laid-open Patent Publication No. 2007-43642discloses an evaluation by extracting a characteristic amount of apicture using decoded data. Also, Japanese Laid-open Patent PublicationNo. 2006-33722 discloses a determination on a degradation state bycreating reference data as preliminary data on a transmission side andusing the reference data without using decoded data, which is not NR(Newton-Raphson) method not using an original image or informationthereof. Japanese Laid-open Patent Publication No. 2002-325254 adetermination on how many packets are lost with respect to one pictureof decoded video while the decoding is a precondition.

SUMMARY

An information processing apparatus includes: a reception unitconfigured to receive a packet string in which packet groups includingdata on a plurality of video frames and having an identifier indicatinga beginning of the video frame assigned to respective packets includingeach initial part of the plurality of video frames are arranged in avideo reproduction order; a counting unit configured to count a numberof received packets corresponding to each of the plurality of videoframes based on respective initial packets in the packet string; and ageneration unit configured to generate video quality estimationinformation for each of the plurality of video frames to estimate aquality of the video in which the plurality of video frames are decodedon a reception terminal based on the number of received packetscorresponding to each of the plurality of video frames.

The object and advantages of the invention will be realized and attainedby at least the feature, elements, and combinations particularly pointedout in the claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a configuration example of an information processingapparatus;

FIG. 2 illustrates an example of a packetization of video data based onMPEG-2 TS;

FIG. 3 is an explanatory diagram for describing a header format of a TSpacket based on MPEG-2 TS;

FIG. 4 illustrates an example of a statistical information table;

FIG. 5 illustrates an example of a reproduction importance level table;

FIG. 6 illustrates an example of a processing flow of the informationprocessing apparatus;

FIG. 7 illustrates a configuration example of the information processingapparatus;

FIG. 8 illustrates examples of a processing of detecting the number oflost packets and a processing of calculating the total packets in avideo frame including the lost packets;

FIG. 9A illustrates an example of the processing flow of the informationprocessing apparatus;

FIG. 9B illustrates an example of the processing flow of the informationprocessing apparatus;

FIG. 9C illustrates an example of the processing flow of the informationprocessing apparatus;

FIG. 10 illustrates a configuration example of the informationprocessing apparatus;

FIG. 11 is an explanatory diagram for describing a periodicity of thevideo frame;

FIG. 12 is a flow chart illustrating an example of an investigationprocessing on the periodicity by a period determination unit; and

FIG. 13 is a flow chart illustrating an example of a detectionprocessing for a lost initial packet by the period determination unit.

DESCRIPTION OF EMBODIMENTS

Accordingly, it is an object of one aspect of the present invention toprovide an information processing apparatus that efficiently generatesinformation for estimating a quality of a video to be distributed on anetwork.

Hereinafter, example embodiments of the present invention will bedescribed with reference to the accompanying drawings.

First Embodiment

According to a first embodiment, an information processing apparatusreceives video packets flowing on a network that distribute a video andassigns evaluation values to respective video frames reproduced from thereceived video packet group.

FIG. 1 illustrates configuration examples of a video distribution systemand an information processing apparatus. The video distribution systemincludes a content server 6, a video distribution server 5, a network 3,a reception terminal 2, an information processing apparatus 1, and amonitor server 4.

The content server 6 is a server for providing a video distributionservice. The content server 6 holds a video content to be distributed onthe network 3. The content server 6 is connected to the videodistribution server 5 and transmits the video content to the videodistribution server 5 as a data stream based on MPEG-2 TS (MovingPicture Experts Group phase 2 Transport Stream).

The video distribution server 5 is connected to the network 3. The videodistribution server 5 performs, for example, an encryption on the datastream based on MPEG-2 TS received from the content server 6 andtransmits the data stream via the network to the reception terminal 2having a subscription for the video distribution service. The videodistribution server 5 is, for example, a server managed by acommunication carrier. The network 3 is, for example, an IP (InternetProtocol) network.

The data stream transmitted to the network 3 is branched during thenetwork transmission. One component of the branched data stream isreceived by the reception terminal 2, and the other component isreceived by the information processing apparatus 1.

The reception terminal 2 is a terminal having the subscription for thevideo distribution service provided by the content server 6. Thereception terminal 2 is connected to the network 3 and receives a streamof IP packet group transmitted from the content server 6 via the videodistribution server 5. The reception terminal 2 outputs a video obtainedby decoding the received stream of IP packet group to a displayapparatus and provides the video to a user.

The information processing apparatus 1 is located between the network 3and the reception terminal 2 and is closer to the reception terminal 2.Through a transmission path between the network 3 and the receptionterminal 2, the information processing apparatus 1 receives the samestream as the stream of IP packet group transmitted to the receptionterminal 2. From the received stream of IP packet group, the informationprocessing apparatus 1 generates information for estimating a quality ofeach of the video frames constituting the video transmitted to thereception terminal 2. The information processing apparatus 1 transmitsthe generated information for estimating the quality of the video to themonitor server 4. A detail of the information processing apparatus 1will be described below.

The monitor server 4 receives the information for estimating the qualityof the video from the information processing apparatus 1.

The data stream flowing on the network 3 is a plurality of IP packetgroups storing video and audio data. The IP packet group is generated inthe following manner.

FIG. 2 illustrates an example of a packetization of video data based onMPEG-2 TS. MPEG-2 TS is a specification standard for multiplexing videoand audio for transmission.

The content server 6 compresses and encodes the video and audio of thecontent that should be transmitted to the reception terminal 2,respectively, for example, on the basis of MPEG-2 video, MPEG-2 audio,and the like to generate a bit string. In the example illustrated inFIG. 2, the bit string of the compressed and encoded video is displayed.This bit string of the video is a set of a plurality of video frame datablocks corresponding to a plurality of video frames. The video framerefers to one image among a plurality of images constituting the videocontent.

The content server 6 divides the generated bit string of the video datainto a predetermined size. For example, the generated bit string of thevideo is divided into each video frame.

The content server 6 further divides the respective video frames into aplurality of fragments and adds a TS header to each fragment to generatea TS packet. The TS packet including an initial byte of each video isreferred to as “initial packet” according to the first embodiment.

The content server 6 further adds an IP header to each TS packet togenerate an IP packet group. In a destination IP address of the IPheader, an IP address of the video distribution server 5 is stored. Thecontent server 6 transmits the generated IP packet group to the videodistribution server 5.

When the video distribution server 5 receives the IP packet group fromthe content server 6, the video distribution server 5 removes therespective IP headers and the TS headers from the IP packet group andperforms an encryption on the fragmented video data (pay load). Thisencryption is, for example, a security for allowing only subscribers forthe video distribution service of the content server 6 to view thevideo. The video distribution server 5 assigns the TS header to eachencrypted pay load again to generate the TS packet. The videodistribution server 5 assigns the IP header in which an IP multicast forspecifying the subscriber for the video distribution service of thecontent server 6 (including the reception terminal 2 and the informationprocessing apparatus 1) is stored as a destination IP address to each TSpacket to generate the IP packet group. The video distribution server 5sends out the generated IP packet group to the network 3.

In the above-mentioned manner, the reception terminal 2 and theinformation processing apparatus 1 can receive the IP packet group fromthe network 3.

Configuration Example of the Information Processing Apparatus

The information processing apparatus 1 is, for example, a general-usecomputer such as a personal computer or a dedicated-use computer thatgenerates the information for estimating the quality of the video. Theinformation processing apparatus 1 includes an input unit 11, aprocessor 12, a storage unit 13, and an output unit 14.

The input unit 11 and the output unit 14 are network interfaces. Thenetwork interface is, for example, a LAN (Local Area Network) interfaceboard or a wireless communication circuit for a wireless communication.The input unit 11 receives the IP packet group flowing on the network 3.The IP packet group input to the input unit 11 also includes the IPpacket including the video data that is received by the receptionterminal 2 connected to the network 3.

The input unit 11 performs a processing based on the IP header such as achange of the order of the received IP packets, for example. The inputunit 11 changes the order of the IP packet groups of the videotransmitted from the content server 6 in a reproduction order. Also, theinput unit 11 removes the IP header of the received IP packet to beoutput to the processor 12. For example, the input unit 11 receives theIP packet including the TS (Transport Stream) packet for transmittingthe video data, removes the IP header, and takes out the TS packet fromthe IP packet to be output to the processor 12.

The storage unit 13 holds a video quality estimation informationgeneration program 13-3. The storage unit 13 is a main storage apparatusand/or an auxiliary storage apparatus, for example. The main storageapparatus includes, for example, a RAM (Random Access Memory) or a ROM(Read Only Memory). The auxiliary storage apparatus is, for example, anEPROM (Erasable Programmable ROM) or a hard disc drive (HDD). Also, theauxiliary storage apparatus may include a removable medium, that is, aportable recording medium. The removable medium is, for example, a discrecording medium such as a USB (Universal Serial Bus) memory or a CD(Compact Disc). The storage unit 13 has a reproduction importance leveltable 13-1 and a statistical information table 13-2. Details of thereproduction importance level table 13-1 and the statistical informationtable 13-2 will be described below.

The processor 12 is, for example, a CPU (Central Processing Unit) or aDSP (Data Signal Processor). The processor 12 executes variousprocessings by executing an OS and various application programs held inthe storage unit 13. The processor 12 can realize a TS packet receptionunit 121, a header analysis unit 122, a packet count unit 123, a tablemanagement unit 124, and a reproduction quality estimation unit 125 byexecuting the video quality estimation information generation program13-3 held in the storage unit 13.

The TS packet reception unit 121 (input unit) accepts only the TS packetamong the packets received from the input unit 11 into the processor 12.The packet group input to the TS packet reception unit 121 is packetstrings arranged in the reproduction order. The TS packet reception unit121 outputs the TS packet to the header analysis unit 122.

To the header analysis unit 122 (calculation unit), the TS packet isinput from the TS packet reception unit 121. The header analysis unit122 analyzes the header of the TS packet.

FIG. 3 is an explanatory diagram for describing a header format of a TSpacket based on MPEG-2 TS.

The TS packet based on MPEG-2 TS has a fixed length of 188 bytes. The TSpacket has a header and a data part (pay load).

Examples of information contained in the header of the TS packetincludes a synchronization byte 51, an initial flag 52, a packet ID 53,a continuity counter 54, and the like.

The synchronization byte 51 has 8 bits and indicates an initial byte ofthe TS packet. As the TS packet has the fixed length of 188 bytes, thesynchronization byte 51 appears every 188 bytes.

The initial flag 52 has 1 bit and is an identifier indicating that therelevant TS packet is at the beginning of the frame as the initialpacket of the video frame or the audio frame. That is, in a case wherethe initial flag 52 of a certain TS packet is, for example, “1”, thisindicates that the data part of the TS packet includes the initial byteof the video frame or the audio frame. Also, in a case where the initialflag 52 of the TS packet is, for example, “0”, this indicates that thedata part of the TS packet includes an intermediate part or trailingpart of the video frame or the audio frame.

The packet ID (Packet Identifier) 53 has 13 bits. When the valueindicated by the packet ID 53 is referred to with a PAT (ProgramAssociation Table) packet and a PMT (Program MAP Table) packet, forexample, audio data, video data, or other data of which type of aprogram included in the data part of the relevant TS packet isindicated. The PAT packet has the packet ID of 0x0000 and is, forexample, a packet including the packet ID corresponding to each programincluded in the stream of the TS packets. The PMT packet has the packetID corresponding to one program among the programs included in the PATpacket and is a packet including the packet ID corresponding to theaudio data, the video data, or the other data included in the programcorresponding to the relevant packet ID. Each TS packet generated fromthe same video is assigned with the packet ID of the same value. Forexample, all the TS packets generated from the video included in acertain one content distributed from the content server 6 are assignedwith the same packet ID. It should be noted that the PAT packet and thePMT packet are not encrypted.

The continuity counter 54 has four bits and indicates a continuity ofthe packets for each packet ID. The continuity counter is for valuesfrom 0 to 15 and is increased by 1 for each TS packet of the same packetID. When the value of the continuity counter is 15, the value of thecontinuity counter of the TS packets of the next same packet IP isreturned to 0.

Hereinafter, the TS packet storing the video data in the data part isreferred to as “video packet”, and the TS packet storing the audiopacket in the data part is referred to as “audio packet”.

The header analysis unit 122 identifies whether the TS packet is thevideo packet or the audio packet from the packet ID of the header of thereceived TS packet. Also, the header analysis unit 122 determineswhether the initial flag of the header of the TS packet is “1” or “0” todetermine whether the TS packet is the initial packet or not. Also, theheader analysis unit 122 checks the continuity counter of the header ofthe TS packet to check the continuity of the received TS packet group.The check result of the continuity counter is not used according to thefirst embodiment. It should be noted that an embodiment where the checkresult of the continuity counter is used will be described below.

As a result of the analysis on the header of the TS packet, in a casewhere the TS packet is the video packet, the header analysis unit 122outputs the analysis result on the header of the TS packet to the packetcount unit 123.

To the packet count unit 123, the analysis result on the header of theTS packet that is the video packet is input from the header analysisunit 122. The packet count unit 123 counts the number of the videopackets input from the header analysis unit 122 for each video frame.Also, the packet count unit 123 counts the number of video framesreceived by the information processing apparatus 1.

In a case where the video packet input from the header analysis unit 122is the initial packet, the packet count unit 123 outputs the countedvalue of the video packets held by the packet count unit 123 at thattime and the counted value of the video frames to the table managementunit 124. Next, the packet count unit 123 resets the counted value ofthe video packets to 0 and counts the received initial packets. Thecounted value of the video packets is 1. Also, the packet count unit 123adds 1 to the counted value of the video frames.

For example, in a case where the counted value of the video packets heldby the packet count unit 123 is 50 and the counted value of the videoframes is 15, the packet count unit 123 receives the initial packets. Inthis case, the packet count unit 123 outputs the counted value of thevideo packets held at that time which is 50 and the counted value of thevideo frames which is 15 to the table management unit 124. Next, thepacket count unit 123 resets the counted value of the video packets to0, counts the received initial packets, and adds 1 to the counted valueof the video packets. Also, the packet count unit 123 adds 1 to thecounted value of the video frames and sets the counted value as 16.

The table management unit 124 receives the counted value of the videopackets and the counted value of the video frames from the packet countunit 123. The table management unit 124 manages the reproductionimportance level table 13-1 and the statistical information table 13-2held in the storage unit 13, on the basis of the counted value of thevideo packets and the counted value of the video frames input from thepacket count unit 123.

FIG. 4 illustrates an example of a statistical information table. Thestatistical information table illustrated in FIG. 4 stores the countedvalue of the video frames input from the packet count unit 123 as aframe number. Also, the counted value of the video packets is associatedwith a frame number indicating the counted value of the video frameswhich are also input to be stored as a packet number of the relevantvideo frame.

When a counted value of the video packets and a counted value n of thevideo frames (natural number that does not include 0) is input from thepacket count unit 123, the table management unit 124 records the countedvalue n of the video frames in the statistical information table 13-2 asthe frame number. Also, the table management unit 124 records thecounted value of the video packets as the packet number included in thevideo frame of a frame number n in the statistical information table13-2. The frame number is a number for the information processingapparatus 1 to identify the video frame within the informationprocessing apparatus 1.

FIG. 5 illustrates an example of a reproduction importance level table.In the reproduction importance level table, evaluation values previouslyassigned to the video frames by an administrator or the like are setstepwise in accordance with the number of packets. The evaluation valuespreviously assigned to the video frames are information for estimatingthe video frames. The evaluation values include, for example,reproduction importance levels, degradation quality values, and thelike. The reproduction importance levels are values indicating thereproduction importance levels of the respective video frames. Thedegradation quality values are values indicating influence levelsaffecting on the quality of the video in a case where the video frame islost during the transmission.

In the example illustrated in FIG. 5, the number of packets are dividedinto three stages of 0 to P1, P1+1 to P2, and P2+1 or more, and theseare respectively assigned with reproduction importance levels X1, X2,and X3. Each of P1 and P2 is a natural number not including 0, and P1<P2is established.

A state in which the number of video packets included in the video frameis large indicates that the information amount that the relevant videoframe has is large and the importance level of the relevant video framein the video is high. Thus, in the example illustrated in FIG. 5, thelarger number of packets (counted value) is assigned with a largerreproduction importance level. That is, in the example illustrated inFIG. 5, the reproduction importance levels are assigned to establishX1<X2<X3.

Also, together with the reproduction importance levels, the degradationquality values can also be assigned in accordance with the number ofpackets. The degradation quality values are values indicating degrees ofthe influence affecting on the quality of the video in a case where acertain video frame is lost. It is conceivable that as the number ofpackets (counted value) is larger, the influence affecting on thequality of the video is larger in a case where the relevant video frameis lost. Thus, the degradation quality value is assigned with the largervalue as the number of packets is larger like the reproductionimportance levels. In the example illustrated in FIG. 5, the video framein which the number of packets is 0 to P1 is assigned with thedegradation quality values D1. Furthermore, the video frame in which thenumber of packets is P1+1 to P2 is assigned with the degradation qualityvalues D2. Then, the video frame in which the number of packets is P2+1or more is assigned with the degradation quality values D3. Also, thedegradation quality values establish D1<D2<D3.

The table management unit 124 classifies the video frame n in accordancewith the number of video packets included in the video frame whilefollowing the reproduction importance level table. It should be notedthat the number n of the video frame is the same number as the framenumber held in the statistical information table 13-2.

The reproduction quality estimation unit 125 monitors the reproductionimportance level table 13-1. When information on the video frame isnewly added in the reproduction importance level table 13-1, thereproduction quality estimation unit 125 reads out the reproductionimportance level of the added video frame from the reproductionimportance level table 13-1 to be transmitted through the output unit 14to the monitor server 4. Also, for example, the reproduction qualityestimation unit 125 may periodically read out the reproductionimportance levels of the respective video frames received by theinformation processing apparatus 1 from the reproduction importancelevel table 13-1 during a predetermined period of time to be transmittedto the monitor server 4. The reproduction importance levels transmittedto the monitor server 4 are displayed, for example, on a display. In themonitor server 4, it is possible to determine the reproductionimportance levels of the respective video frames included in the videotransmitted from the content server 6 to the reception terminal 2.

The information processing apparatus 1 further includes an inputapparatus such as a key board or a pointing device and an outputapparatus such as a display apparatus or a printer as peripheralapparatuses, for example. Also, the input apparatus can include an inputapparatus like a camera for a video or an image and an audio inputapparatus like a microphone, for example. Also, for example, the outputapparatus can include an audio output apparatus like a speaker.

<<Processing Flow of the Information Processing Apparatus>>

FIG. 6 illustrates an example of a processing flow of the informationprocessing apparatus 1. The input unit 11 of the information processingapparatus 1 receives the IP packets flowing on the network 3. The inputunit 11 removes the TS packet from the received IP packets to be outputto the TS packet reception unit 121. The TS packet reception unit 121receives the TS packet from the input unit 11 (OP1). The TS packetreception unit 121 outputs the TS packet to the header analysis unit122.

The header analysis unit 122 analyzes the header of the TS packet inputfrom the TS packet reception unit 121 (OP2). The header analysis unit122 analyzes the packet ID of the header of the TS packet to identifywhether the relevant TS packet is the video packet or the audio packet(OP3). In a case where the TS packet is the audio packet (OP3: No), theprocessing returns to OP1.

In a case where the TS packet is the video packet (OP3: Yes), the headeranalysis unit 122 determines whether or not the relevant TS packet isthe initial packet of the video frame on the basis of the initial flagof the header of the TS packet (OP4). That is, the header analysis unit122 determines whether or not the initial flag in the header of the TSpacket is “1”. The header analysis unit 122 outputs the analysis resultto the packet count unit 123.

The packet count unit 123 receives the analysis result on the initialflag of the header of the TS packet from the header analysis unit 122.In a case where the TS packet is not the initial packet (OP4: No), thepacket count unit 123 adds 1 to a counted value S of the video packets(in FIG. 5, packet count, that is, a value of the counter for countingthe number of packets, S is an integer greater than or equal to 0)(OP5). That is, in a case where the initial flag of the header of the TSpacket is “0”, the packet count unit 123 adds 1 to the counted value Sof the video packets. After that, the processing returns to OP1. Theinitial value of the counted value S of the video packets is 0.

In a case where the TS packet is the initial packet (OP4: Yes), thepacket count unit 123 decides the number of packets S in the video framen on the basis of the counted value S of the video packets and thecounted value n of the video frames held at that time by the packetcount unit 123 (OP6). The counted value n of the frames is representedas a frame count in FIG. 5 and is a value of the counter for countingthe number of frames. The packet count unit 123 outputs the decidednumber of packets S in the video frame n to the table management unit124.

Next, the packet count unit 123 sets the counted value S of the videopackets as 1 (OP7). Also, the packet count unit 123 adds 1 to, thecounted value n of the video frames (OP7).

The table management unit 124 receives the number of packets S in thevideo frame n from the packet count unit 123. The table management unit124 records the number of packets S included in the video frame n in thestatistical information table 13-2 (OP8, see FIG. 4).

Next, the table management unit 124 records an identification number nof the video packet in the reproduction importance level table 13-1 inaccordance with the number of packets (updates the reproductionimportance level table 13-1) (OP9, see FIG. 5).

When the reproduction importance level table 13-1 is updated, thereproduction quality estimation unit 125 reads out the reproductionimportance level of the video frame n from the reproduction importancelevel table 13-1 to be output to the monitor server 4 (OP10). Afterthat, the processing returns to OP1

Actions and Effects of the First Embodiment

The information processing apparatus 1 receives the same video packet asthe video packet received by the reception terminal 2 flowing on thenetwork 3, estimates the number of packets included in the video packeton the basis of the header of the video packet, and assigns thereproduction importance level to the video frame in accordance with thenumber of packets. According to the information processing apparatus 1,with the information on the header of the video packet, withoutrestoring the video frame from the video packet group, it is possible toefficiently assign the reproduction importance levels (information forestimating the quality of the video, video quality estimationinformation) to the video frame.

Also, even in a case where the data stored in the data part of the TSpacket is encrypted, the information processing apparatus 1 canappropriately assign the reproduction importance level to the videoframe by analyzing the header of the non-encrypted TS packet.

According to the first embodiment, in accordance with the number ofpackets in the video frame, in the reproduction importance level table13-1, the video frames are classified, and the reproduction importancelevels are decided. Instead of this, the reproduction importance leveltable 13-1 may assign an identifier of the group in accordance with thenumber of packets as the reproduction importance level instead of thenumeric value. That is, the information for estimating the quality ofthe video generated for each of the video frame (the evaluation value,the reproduction importance level, the degradation quality value) is notlimited to a numeric value but may also be a alphanumeric character orthe like used as an identifier for the group in accordance with thenumber of the packets.

Also, according to the first embodiment, when the reproductionimportance level table 13-1 is updated, the reproduction qualityestimation unit 125 reads out the reproduction importance level of thenewly added video frame from the reproduction importance level table13-1 to be transmitted to the monitor server 4. Instead of this, thereproduction quality estimation unit 125 transmits the reproductionimportance level table 13-1 to a display (not illustrated in thedrawing) that is provided to the information processing apparatus 1, andthe transmitted reproduction importance level table 13-1 may bedisplayed on the display.

Second Embodiment

According to a second embodiment, in a case where the video packet whichis lost during the transmission exists, the information processingapparatus 1 detects the loss of the video packet and assigns the degreeaffecting the quality of the video by the loss of the video packet asthe evaluation value. According to the second embodiment, a case issupposed in which the initial packet is not lost. It should be notedthat according to the second embodiment, a description of a partsubstantially common to the first embodiment will be omitted.

Configuration Example of the Information Processing Apparatus

FIG. 7 illustrates a configuration example of the information processingapparatus 1 according to the second embodiment. According to the secondembodiment, substantially similar as in the first embodiment, theinformation processing apparatus 1 is provided with the input unit 11,the processor 12, the storage unit 13, and the output unit 14. Thestorage unit 13 holds a video quality estimation information generationprogram 13-4.

By executing the video quality estimation information generation program13-4 held in the storage unit 13, the processor 12 can further realize alost packet detection unit 126 in addition to the TS packet receptionunit 121, the header analysis unit 122, the packet count unit 123, thetable management unit 124, and the reproduction quality estimation unit125 described according to the first embodiment.

When the TS packet is input, the TS packet reception unit 121accumulates the TS packet in a buffer provided in a storage area of thestorage unit 13.

Substantially similar as in the first embodiment, when the TS packet isreceived, on the basis of the header of the TS packet, the headeranalysis unit 122 analyzes the initial flag, the packet ID, and thecontinuity counter. The header analysis unit 122 detects the loss of theTS packet by analyzing the continuity counter of the TS packets inaddition to the processing described according to the first embodiment.

For example, the header analysis unit 122 detects the loss of the TSpacket in the following manner. The header analysis unit 122 determineswhether or not the value represented by the continuity counter of thereceived TS packets is the value obtaining by adding 1 to the valuerepresented by the continuity counter of the immediately preceding TSpackets having the same packet ID. That is, the header analysis unit 122determines whether or not the values of the continuity counter of thereceived TS packet and the immediately preceding TS packet having thesame packet ID are continuous. In a case where the values of thecontinuity counter of the received TS packet and the immediatelypreceding TS packet are continuous, the header analysis unit 122determines that no loss of the TS packet occurs. In a case where thevalues of the continuity counter of the received TS packet and theimmediately preceding TS packet are not continuous, the header analysisunit 122 determines that the loss of the TS packet occurs.

In a case where the loss of the TS packet is detected, the headeranalysis unit 122 notifies the lost packet detection unit 126 of theloss of the TS packet.

Substantially Similar as in the processing described according to thefirst embodiment, in a case where the TS packet is the initial packet,the packet count unit 123 outputs the counted value of the video packetsand the counted value of the video frames held at that time to the tablemanagement unit 124 and the lost packet detection unit 126.

The lost packet detection unit 126 receives notification on the loss ofthe TS packet from the header analysis unit 122. The lost packetdetection unit 126 analyzes the TS packets accumulated in the buffer ofthe storage unit 13 and detects the number of the lost TS packets.

Also, when the counted value of the video packets and the counted valueof the video frames are received from the packet count unit 123, thelost packet detection unit 126 obtains a total number of packets in therelevant video frame including the number of the lost TS packets.

FIG. 8 illustrates examples of a processing of detecting the number oflost packets by the lost packet detection unit 126 and a processing ofcalculating the total number of packets of the video frames includingthe lost packets. In the example illustrated in FIG. 8, a case isillustrated in which several packets are lost among the video frameincluded in the video frame n.

In the example illustrated in FIG. 8, the value of the continuitycounter for the TS packet P1 included in the video frame n is M (M is aninteger greater than or equal to 0). The value of the continuity counterfor the TS packet P2 after the TS packet P1 is N (N is an integergreater than or equal to 0). The value of the continuity counter M forthe TS packet P1 and the value of the continuity counter N for the TSpacket are not continuous, and the header analysis unit 122 detects thatthe TS packet is lost between the TS packet P1 and the TS packet P2.

Also, both the TS packet P1 and the TS packet P2 have the same packet IDand are the video packets. Also, both the TS packet P1 and the TS packetP2 are not the initial packets.

When the lost packet detection unit 126 is notified from the headeranalysis unit 122 that the lost packet is detected between the TS packetP1 and the TS packet P2, the lost packet detection unit 126 reads outthe TS packet P1 and the TS packet P2 held in the buffer of the storageunit 13. The lost packet detection unit 126 detects the number of lostpackets on the basis of the value M indicated by the continuity counterof the TS packets P1 and the value N indicated by the continuity counterof the TS packets P2. In the case of M<N, the lost packet detection unit126 subtracts the value of the continuity counter M for the TS packet P1from the value of the continuity counter N for the TS packet P2 andfurther subtracts 1 to detect the number of lost packets. In the case ofM≧N, the lost packet detection unit 126 subtracts the value of thecontinuity counter M for the TS packet P1 from 15 and adds the value ofthe continuity counter N for the TS packet P2 to detect the number oflost packets.

Number of lost packets=N−M−1(in the case of M<N)

Number of lost packets=15−M+N(in the case of M≧N)

The lost packet detection unit 126 holds the detected number of lostpackets. The lost packet detection unit 126 receives the counted value nof the video frames and the counted value S of the video packets fromthe packet count unit 123. The counted value S of the video packetsreceived from the packet count unit 123 is the number of actual packetsof the video packets actually received by the information processingapparatus 1. The lost packet detection unit 126 obtains the total numberof packets in the video frame including the number of lost packets. Itshould be noted that the video frame n in FIG. 8 is the video frame tobe lost as the packet is lost.

The lost packet detection unit 126 adds the number S of the actualpackets in the video frame n with the number of lost packets tocalculate the total number of packets in the video frame.

The total number of packets in the video frame=the number S of actualpackets+the number of lost packets

The lost packet detection unit 126 outputs the calculated total numberof packets in the video frame n to the reproduction quality estimationunit 125.

When the total number of packets in the video frame is received from thelost packet detection unit 126, the reproduction quality estimation unit125 reads out the degradation quality value of the video frame n inaccordance with the number of total packets from the reproductionimportance level table to be transmitted through the output unit 14 tothe monitor server 4.

In the monitor server 4, the degradation quality value of the videoframe is received. The monitor server 4 adds, for example, the receiveddegradation quality value of the video frame and estimates the qualityof the video received by the reception terminal 2 on the basis of theadded degradation quality value.

<<Processing Flow of the Information Processing Apparatus>>

FIG. 9A, FIG. 9B, and FIG. 9C illustrate examples of the processing flowof the information processing apparatus 1. The processing in a casewhere the lost packet does not exist is substantially similar to that ofthe first embodiment, and a description will be given of a case wherethe lost packet is detected. Also, hereinafter, a description will begiven of a case where the TS packet P2 and the TS packet P3 in theexample illustrated in FIG. 8 are processed.

The TS packet reception unit 121 receives the TS packet P2 thought theinput unit 11 (OP11). The TS packet reception unit 121 outputs the TSpacket P2 to the header analysis unit 122.

The header analysis unit 122 analyzes the header of the TS packet P2input from the TS packet reception unit 121. The header analysis unit122 determines whether the TS packet P2 is the video packet or the audiopacket on the basis of the packet ID of the header of the TS packet P2(OP12). For example, when a value “1” of the packet ID is set as a valueindicating the video packet, the TS packet P2 is the video packet (OP12:Yes), and next, the header analysis unit 122 determines whether or notthe initial flag of the TS packet P2 is “1”. That is, the headeranalysis unit 122 determines whether or not the TS packet P2 is theinitial packet (OP13).

As the TS packet P2 is not the initial packet (OP13: No), the headeranalysis unit 122 next determines whether or not the lost packet existson the basis of the respective continuity counters of the TS packets P2and the TS packets P1 immediately before the TS packets P2 (OP14). Thatis, the header analysis unit 122 determines whether or not the value ofthe continuity counter M for the TS packet P1 and the value of thecontinuity counter N for the TS packet P2 are continuous values. In theexample illustrated in FIG. 8, the value of the continuity counter M forthe TS packet P1 and the value of the continuity counter N for the TSpacket P2 are not continuous values, and thus the header analysis unit122 determines that no continuity exists, that is, the lost packetexists (OP14: No). The header analysis unit 122 notifies the lost packetdetection unit 126 that the lost packet exists between the TS packet P1and the TS packet P2. Also, the header analysis unit 122 outputs theanalysis result on the header of the TS packet P2 to the packet countunit 123.

When the lost packet detection unit 126 is notified from the headeranalysis unit 122 that the lost packet exists between the TS packet P1and the TS packet P2, the lost packet detection unit 126 detects thenumber of lost packets (OP15).

The lost packet detection unit 126 determines whether or not the value Nindicated by the continuity counter of the TS packets P2 is larger thanthe value M indicated by the continuity counter of the TS packets P1(FIG. 9B, OP151). In a case where the value N indicated by thecontinuity counter of the TS packets P2 is greater than the value Mindicated by the continuity counter of the TS packets P1 (OP151: Yes),the lost packet detection unit 126 obtains the number of lostpackets=N−M−1 (OP152). The lost packet detection unit 126 holds thenumber of lost packets.

In a case where the value N indicated by the continuity counter of theTS packets P2 is less than or equal to the value M indicated by thecontinuity counter of the TS packets P1 (OP151: No), the lost packetdetection unit 126 obtains the number of lost packets=15−M+N (OP153).The lost packet detection unit 126 holds the number of lost packets.

When the analysis result on the header of the TS packet P2 is receivedfrom the header analysis unit 122, the packet count unit 123 adds 1 tothe counted value S of the video packets in the video frame n as the TSpacket P2 is not the initial packet on the basis of the analysis resulton the header (FIG. 9A, OP16). After that, the processing returns toOP11.

Subsequently, in the example illustrated in FIG. 8, a case will bedescribed in which the TS packet P3 that is the initial packet in avideo frame n+1 which follows the video frame n is processed.

The TS packet reception unit 121 receives the TS packet P3 through theinput unit 11 (OP11). The TS packet reception unit 121 outputs the TSpacket P3 to the header analysis unit 122.

The header analysis unit 122 analyzes the header of the TS packet P3input from the TS packet reception unit 121. The header analysis unit122 determines whether the TS packet P3 is the video packet or the audiopacket on the basis of the packet ID of the header of the TS packet P3(OP12). For example, if a value “2” of the packet ID indicates the videopacket, as the TS packet is the video packet (OP12: Yes), the headeranalysis unit 122 determines next whether or not the TS packet P3 is theinitial packet (OP13). As the TS packet P3 is the initial packet (OP13:Yes), the header analysis unit 122 outputs the analysis result on theheader of the TS packet P3 to the packet count unit 123, and theprocessing progresses to OP17.

When the analysis result including the notification indicating that theTS packet P3 is the initial packet is received from the header analysisunit 122, the packet count unit 123 decides the number of packets S inthe video frame n on the basis of the counted value S of the videopackets and the counted value n of the video frames held at that time(OP17). The packet count unit 123 outputs the number of packets S in thevideo frame n to the table management unit 124 and the lost packetdetection unit 126.

In the video frame n, the loss of the packet is detected between the TSpacket P1 and the TS packet P2 (OP18: Yes). Therefore, the lost packetdetection unit 126 calculates the total number of packets in the videoframe when the number of packets S in the video frame n is received fromthe table management unit 124 (OP19).

The lost packet detection unit 126 adds the number of lost packets heldin the received number of packets S in the video frame n to calculatethe total number of packets in the video frame (FIG. 9C, OP191). Thelost packet detection unit 126 outputs the calculated total number ofpackets in the video frame n to the reproduction quality estimation unit125.

When the total number of packets in the video frame is received from thelost packet detection unit 126, the reproduction quality estimation unit125 refers to the reproduction importance level table 13-1 and reads outthe degradation quality values in accordance with the total number ofpackets in the video frame n (OP192).

The reproduction quality estimation unit 125 transmits the degradationquality value of the video frame n to the monitor server 4 through theoutput unit 14 (OP193).

Next, the packet count unit 123 sets the counted value S of the videopackets as 1. Also, the packet count unit 123 adds 1 to, the countedvalue n of the video frames (FIG. 9A, OP20).

When the number of packets S in the video frame n is received from thepacket count unit 123, the table management unit 124 records the numberof packets S in the statistical information table 13-2 and classifiesthe video frame n in accordance with the total number of packets in thevideo frame n to be recorded in the reproduction importance level table13-1 (OP21).

When the reproduction importance level table 13-1 is updated, thereproduction quality estimation unit 125 reads out the reproductionimportance level of the video frame n from the reproduction importancelevel table 13-1 to be output to the monitor server 4 (OP22). Afterthat, the processing returns to OP11.

Actions and Effects of the Second Embodiment

The information processing apparatus 1 according to the secondembodiment analyzes the header of the received TS packet and detects theloss of the TS packet in a case where the values of the continuitycounter are not continuous. According to the information processingapparatus 1, without restoring the video frame from the received TSpacket, by analyzing the header of the TS packet, it is possible todetect the loss of the TS packet and the number of lost packets. Also,according to the information processing apparatus 1, the number of lostpackets is detected so that the total number of packets in the videoframe including the lost packet can be calculated, and in accordancewith the total number of packets, the degradation quality value can beassigned to the video frame including the lost packet (qualityestimation information can be generated). As the degradation qualityvalue is assigned to the video frame including the lost packet to bedistributed on the network 3, it is possible to estimate the quality ofthe video received by the reception terminal 2.

Also, the video frame group having the periodicity in the size of thevideo frames is distributed on the network 3, and even in a case wherethe period suddenly changes, the information processing apparatus 1according to the second embodiment can assign the evaluation values tothe lost video frame and the respective video frame. The video framegroups having the periodicity of the size of the video frames includesvideo frame groups such as, for example, the I picture, P picture, and Bpicture of MPEG-2. Also, in a case where the periodicity of the size ofthe video frame suddenly changes, for example, in a service distributingthe IPTV, a case exists in which the video is switched from a program toa commercial film. On the basis of the information the header of thereceived TS packets, the information processing apparatus 1 detects thetotal number of packets included in the video frame including the lostpacket and assigns the degradation quality value in accordance with thetotal number of packets, so that even in a case where the periodicity ofthe size of the video frame (the number of packets) suddenly changes, itis possible to appropriately assign the evaluation value to the videoframe.

Third Embodiment

The information processing apparatus according to a third embodimentmonitors a periodicity of the number of the packets included in thevideo frame and detects the loss of the video packet. According to thethird embodiment, it is assumed that the frame rate of the videodistributed on the network 3 is 30 fps, for example. Also, according tothe second embodiment, the loss of the initial packet is not supposed,but according to the third embodiment, the packet loss including anoccurrence of the initial packet loss is supposed. It should be notedthat according to the third embodiment, a description substantiallycommon to the first embodiment and the second embodiment will beomitted.

FIG. 10 illustrates a configuration example of the informationprocessing apparatus 1 according to the third embodiment. According tothe third embodiment, substantially similar as in the first embodimentand the second embodiment, the information processing apparatus 1 isprovided with the input unit 11, the processor 12, the storage unit 13,and the output unit 14. The storage unit 13 holds a video qualityestimation information generation program 13-5.

By executing the video quality estimation information generation program13-5 held in the storage unit 13, the processor 12 can realize a perioddetermination unit 127 in addition to the TS packet reception unit 121,the header analysis unit 122, the packet count unit 123, the tablemanagement unit 124, the reproduction quality estimation unit 125, andthe lost packet detection unit 126 described according to the firstembodiment and the second embodiment.

The period determination unit 127 monitors the reproduction importancelevel table 13-1 and detects the loss of the initial packet on the basisof the periodicity of the number of packets in the received video frame.

FIG. 11 is an explanatory diagram for describing a periodicity of thevideo frame. In the example illustrated in FIG. 11, a video frame groupwhose frame rate is 30 fps (Frame Per Second) is illustrated. In thecase of the video whose frame rate is 30 fps, 30 pieces of video framesare reproduced in one second. Also, for example, in a case where theMPEG-2 encoding is applied, in a period of the one frame every 15frames, like I picture (Intra Picture) of MPEG-2, the video frame havingthe number of video packets greater than that of the other video framesappears. For example, in a case where the reproduction importance leveltable illustrated in FIG. 5 is set, the video frame larger than theabove-mentioned other video frames is a video frame classified into agroup where the number of packets is the greatest (the number of packetsis greater than or equal to P2+1). The video frame described above thathas the number of packets greater than that of the other video frames isreferred to as key frame. That is, in the MPEG-2 encoded video whoseframe rate is 30 fps, 15 pieces of video frames are reproduced in 0.5seconds, and one of the video frames is the key frame.

The period determination unit 127 monitors the reproduction importancelevel table 13-1, and when the key frame appears, the video packetsincluded in the video frame group that should be reproduced in 0.5seconds while the key frame is set as the beginning are investigated.

The header of the TS packet has a field where information indicating areference value of a system clock is stored. For example, in the case ofMPEG-2 TS, a time stamp based on a clock synchronized on the videodistribution side and the video reception side is stored in PCR (ProgramClock Reference) in an adaptation field in the header of the TS packet.By referring to the PCR of the header of the TS packet, for example, byinspecting a difference with the PCR of the initial packet in the keyframe, the period determination unit 127 can detect the video packetsincluded in the video frames that should be reproduced in 0.5 secondswhile the key frame is set as the beginning. It should be noted that thevideo packets are accumulated in the buffer of the storage unit 13 bythe TS packet reception unit 121, and the period determination unit 127detects the video packet from the buffer of the storage unit 13.

FIG. 12 is a flow chart illustrating an example of an investigationprocessing on the periodicity by the period determination unit 127. Theperiod determination unit 127 monitors the reproduction importance leveltable 13-1 and detects the key frame classified into the group where thenumber of packets is greater than or equal to P2 (OP31).

The period determination unit 127 detects the video packet groupincluded in the time frame of 0.5 seconds at the time of thereproduction while the key frame is set as the beginning from the bufferin the storage unit 13 (OP32).

The period determination unit 127 determines whether or not 15 initialpackets (packets whose initial flag is “1”) are included in the videopacket group in the time frame of 0.5 seconds at the time of thereproduction while the detected key frame is set as the beginning(OP33). That is, the period determination unit 127 determines whether ornot 15 video frames exist in the time frame of 0.5 seconds at the timeof the reproduction while the key frame is set as the beginning.

In a case where the 15 initial packets are included in the time frame of0.5 seconds at the time of the reproduction while the key frame is setas the beginning (OP33: Yes), as it is indicated that the 15 videoframes exist in the time frame of 0.5 seconds, the period determinationunit 127 determines that the lost video frame does not exist (OP34).

In a case where the number of the initial packets included in the timeframe of 0.5 seconds at the time of the reproduction while the key frameis set as the beginning is less than 15 (OP33: No), the lost initialpacket exists (OP35). The period determination unit 127 analyzes thecontinuity counter of the headers of the respective video packetsincluded in the time frame of 0.5 seconds at the time of thereproduction while the key frame is set as the beginning, the initialflag, and the like to detect the lost initial packet and the lost videoframe.

FIG. 13 is a flow chart illustrating an example of a detectionprocessing for a lost initial packet by the period determination unit127. In FIG. 13, a part of the video packet group included in the videoframes that should be reproduced in 0.5 seconds while the key frame isset as the beginning is illustrated. In the video packet groupillustrated in FIG. 13, only 14 initial packets are included, and the TSpacket L1 that is the initial packet of the video frame n+1 and aplurality of subsequent TS packets are lost. A lower part of FIG. 13illustrates a plurality of lost packets including the lost TS packet L1and the adjacent TS packet 1 and TS packet 2. The TS packet 1 is apacket included in the video frame n.

In the example illustrated in FIG. 13, the period determination unit 127detects that 15 initial packets do not exist in the video packet groupincluded in the time frame of 0.5 seconds at the time of thereproduction while the key frame is set as the beginning which is readout from the buffer of the storage unit 13.

Next, the period determination unit 127 inspects the continuity counterof the detected video packet groups and extracts the video packet whosevalue of the continuity counter is not continuous. In the exampleillustrated in FIG. 13, the value of the continuity counter of the TSpacket 1 is 10, and the value of the continuity counter of the TS packet2 received immediately after the TS packet 1 is 4. Therefore, in theexample illustrated in FIG. 13, the period determination unit 127extracts the TS packet 1 and the TS packet 2.

The period determination unit 127 calculates the number of lost packetson the basis of the value of the continuity counter of the extractedvideo packet. The calculation method is substantially similar to thelost packet detection unit 126. That is, in the example illustrated inFIG. 13, the period determination unit 127 detects 9 (15−M+N=15−10+4) asthe number of lost packets.

The period determination unit 127 regards the lost packets as the TSpackets included in the video frame n+1 to obtain the video frame n andthe number of packets in the video frame n+1. For example, in theexample illustrated in FIG. 13, the period determination unit 127detects the number of the TS packets from the initial packet before theextracted TS packet 1 until the TS packet 1 as the number of packets inthe video frame n. For example, in the example illustrated in FIG. 13,the period determination unit 127 adds 9 which is the detected number oflost packets to the number of the TS packets from the extracted TSpacket 2 until the next initial packet to obtain the number of packetsin the video frame n+1.

The period determination unit 127 outputs the number of packets in thevideo frame n and the number of packets in the video frame n+1 to thereproduction quality estimation unit 125. The period determination unit127 is equivalent to a detection unit.

The reproduction quality estimation unit 125 reads out the degradationquality value in accordance with the number of packets in the videoframe n+1 from the reproduction importance level table 13-1 to betransmitted to the monitor server 4. It should be noted that in theexample illustrated in FIG. 13, the lost packet is not included in thevideo frame n, but the video packet at the end of the video frame n maybe lost. Thus, the degradation quality value of the video frame n isdesirably transmitted to the monitor server 4.

According to the second embodiment, in a case where the packet loss isgenerated substantially similar as in the example illustrated in FIG.13, the video frame n and the video frame n+1 are detected as one videoframe including the lost packet. According to the information processingapparatus of the third embodiment, even in a case where the packet losss generated similarly as in the example illustrated in FIG. 13, it ispossible to appropriately detect the video frame n and the video framen+1.

According to the information processing apparatus of the thirdembodiment, even in a case where the loss of the initial packet occurs,the video frame including the lost packet is appropriately detected, andthe degradation quality value can be assigned to the video frameincluding the lost packet.

Also, substantially similar as in the first embodiment and the secondembodiment, by analyzing the header of the video packet, the informationprocessing apparatus detects the video frame including the lost packetand can assign the evaluation value, which is efficient.

Also, according to the first to third embodiments, the case has beendescribed in which the video is transmitted through MPEG-2 TS, but thespecification is not limited to MPEG-2 TS. For example, the presentinvention can also be applied in a case where the video is transmittedthrough MPEG-2 TTS (Transmitted TS). MPG-2 TTS is obtained by adding afour-byte time stamp to the beginning of the header of the TS packet ofMPEG-2.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the principlesof the invention and the concepts contributed by the inventor tofurthering the art, and are to be construed as being without limitationto such specifically recited examples and conditions, nor does theorganization of such examples in the specification relate to a showingof the superiority and inferiority of the invention. Although theembodiment(s) of the present invention(s) has (have) been described indetail, it should be understood that the various changes, substitutions,and alterations could be made hereto without departing from the spiritand scope of the invention.

1. An information processing apparatus comprising: a reception unit configured to receive a packet string in which packet groups including data on a plurality of video frames and having an identifier indicating a beginning of the video frame assigned to respective packets including each initial part of the plurality of video frames are arranged in a video reproduction order; a counting unit configured to count a number of received packets corresponding to each of the plurality of video frames based on respective initial packets in the packet string; and a generation unit configured to generate video quality estimation information for each of the plurality of video frames to estimate a quality of the video in which the plurality of video frames are decoded on a reception terminal based on the number of received packets corresponding to each of the plurality of video frames.
 2. The information processing apparatus according to claim 1, wherein the counting unit obtains a number obtained by adding 1 to the number of received packets during a period from a time when the initial packet is received until a next initial packet is received as the number of received packets corresponding to one of the plurality of video frames.
 3. The information processing apparatus according to claim 1 further comprising a calculation unit configured to calculate a number of packets lost on a network based on continuous numbers assigned to the respective packets in the packet string received by the reception unit.
 4. The information processing apparatus according to claim 1 further comprising a detection unit configured to detect, while the initial packet in the packet string received by the reception unit is set as the beginning of the video frame, when the number of initial packets included in the plurality of packets that should be reproduced in a predetermined time is less than a predetermined value, a loss of at least one initial packet in the plurality of video packets that should be reproduced in the predetermined time.
 5. An information generation method for causing a computer to execute: receiving a packet string in which packet groups including data on a plurality of video frames and having an identifier indicating a beginning of the video frame assigned to respective packets including each initial part of the plurality of video frames are arranged in a video reproduction order; counting a number of received packets corresponding to each of the plurality of video frames based on respective initial packets in the packet string; and generating video quality estimation information for each of the plurality of video frames to estimate a quality of the video in which the plurality of video frames are decoded on a reception terminal based on the number of received packets corresponding to each of the plurality of video frames.
 6. A computer-readable storage medium including a program to cause an information generation method to execute operations on a computer, the program comprising: receiving a packet string in which packet groups including data on a plurality of video frames and having an identifier indicating a beginning of the video frame assigned to respective packets including each initial part of the plurality of video frames are arranged in a video reproduction order; counting a number of received packets corresponding to each of the plurality of video frames based on respective initial packets in the packet string; and generating video quality estimation information for each of the plurality of video frames to estimate a quality of the video in which the plurality of video frames are decoded on a reception terminal based on the number of received packets corresponding to each of the plurality of video frames. 